Multiaperture magnetic core circuit



Dec. 27, 1966 E. E. NEW/HALL.

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ENA @L /NG CURRENT United States Patent O 3,294,979 MULTIAPERTURE MAGNETIC CURE CIRCUIT Edmundo E. Newhall, Brookside, NJ., assignor to Bell Telephone Laboratories, Incorporated, New York, N.Y., a corporation of New York Filed Mar. 27, 1963, Ser. No. 268,337 Claims. (Cl. 307-88) This invention relates to magnetic core circuits and, more specifically, to a multiapertured magnetic core amplifier which produces an energy gain.

Magnetic circuits which function as power amphfiers are well known. Magnetic amplifiers typically employ square loop, ferromagnetic cores biased near their switching threshold. Input signals are coupled to the cores, which, along with the bias supplied thereto, exceed the core switching threshold thereby inducing amplified output signals in -output windings coupled to the cores. Such power amplifying systems, however, impose exacting tolerances on the magnitude of the biasing signal, and also deliver a fixed magnitude of output power independent of the amplitude of the applied input signal.

In addition, magnetic core transformers have been widely employed as voltage or current amplifiers. In a transformer, input signals, coupled to a core by an input winding, switch flux in the core thereby directly inducing a signal in an output winding. The relative magnitude of the input and output signals is dependent upon the ratio of turns included in the input and output windings which couple the core. Transformers, however, have a theoretical maximum power transferring ability of 100% which in practice can never Abe obtained. Therefore, such arrangements in practice produce an energy loss, and not an energy gain.

It is therefore an object of the present invention to provide an improved magnetic core circuit.

More specifically, an object of the present invention is the provision of a multiapertured core amplifier arrangement which produces a power gain and which allows very wide tolerances on the applied signals.

Another object of the present invention is the provision of a highly reliable magnetic core amplifier which may advantageously -be inexpensively and easily constructed, and is capable of a relatively high operational repetition rate.

These and -other objects of the present invention are realized in a specific illustrative, magnetic core amplifier arrangement including a plurality of multiapertured square loop magnetic cores. Each c-ore includes a driving leg in parallel with a shunt leg of the same cross-sectional area and a cross leg 4is provided to complete a closed magnetic path which also includes the driving leg. The cross leg has a uniform cross-sectional area which is twice the magnitude of that possessed by each of the associated driving and shunt legs, and an aperture is centrally located in the cross leg. The cores are subdivided into buffer cores including cross leg apertures of a like dimension and transformer cores including cross leg apertures of different dimensions, with the ferromagnetic material around each of the transformer core apertures being characterized by a different magnetic -path length. In addition, the transformer cores are each characterized -by a different thickness. A plurality of short-circuited windings are each coupled to the apertures included in one buffer core and two transformer cores, the windings being coupled to the ferromagnetic material on either side of each associated aperture in an opposite polarity.

A driving winding is provided to switch the flux condition of the cores in a sequential manner. As the transformer cores are driven in turn Ibetween a maximum remanent and -a neutral magnetic condition, input information supplied to the transformer core including 3,294,979 Patented Dec. 27, 1966 the smallest aperture is propagated to finally reside in an amplified condition in the largest-apertured transformer core.

It is thus a feature of the present invention that a plurality of square loop, ferromagnetic cores are apertured such that the material on the sides of corresponding apertures included in different cores is characterized by different path lengths.

It is another feature of the present invention that a multiapertured core amplifying arrangement include a plurality of square loop, ferromagnetic `cores each characterized by a different thickness and a different flux capacity.

It is still another feature of the present invention that a magnetic core amplifier comprise a plurality of square loop, ferromagnetic cores each including a cross leg, the cross legs included in different cores lbeing apertured to form shunt magnetic members characterized by different path lengths, an energized winding for sequentially switching flux in the cores, and a plurality of shortcircuited coupling windings linked to selected core apertures.

A complete understanding of the present invention and of the above and other features, advantages and variations thereof may `be gained from a consideration of the following detailed description of an illustrative embodiment thereof presented herein-below in conjunction with the accompanying drawing in which:

FIG. l is a diagram of a specific, illustrative, multiapertured core amplifier arrangement which embodies the principles of the present invention;

FIG. 2 is a diagram of a first magnetic condition for one of the multiapertured cores illustrated in FIG. l;

FIG. 3 is a diagram of a second magnetic condition for the mu-ltiapertured core illustrated in FIG. 2; and

FIG. 4 is a time plot of the current supplied by an enabling source 46 included in FIG. l.

Referring now to FIG. 1, there is shown a specific, illustrative, two-stage, two-channel, magnetic core amplifier arrangement which includes five multiapertured, square loop, ferromagnetic cores 10 through 14. Each core includes two driving legs 20 and 20', each connected in parallel with a shunt leg 21 and 21', respectively. In addition, each -core inc-ludes two cross legs 22 each connecting a junction of the driving leg 20 and the shunt leg 21 with the corresponding junction of the legs 20 and 21. Each of the cross legs 22 has a uniform crosssectional area which is twice the magnitude of that possessed yby each of the driving legs 20 and 20 and the shunt legs 21 and 2.1' associated therewith, all of the aforementioned magnetic legs having a like value of remanent saturation. (Herein, for simplification, ideal square loop materials are assumed. Therefore, the terms saturation and maximum remanence will be used interchangeably.) The cores are subdivided into two buffer cores 11 and 13 each including a like thickness and three transformer cores 10, 12 and 14 each comprising a different thickness. Hence, the cross legs 22 included in each of the buffer cores is characterized Iby a like flux capacity, while the cross legs 22 included in the cores 10, 12 and 14 are characterized by an increasing flux capacity in the order listed. With respect to any single core, each of the cross legs 22 has twice the flux capacity of either of the driving legs 20 and 20 or the shunt legs 21 and 21.

Two apertures 30 and 31 are centrally located on the long axes of the cross legs 22 included in each of the cores 19 through 14. The apertures included in each of the buffer cores 11 and 13 are of like dimensions thereby forming two shunt, equal-length members there-around, the members included in both of the cores 11 and 13 possessing the same path length. The transformer cores 10,

3 12 and 14, conversely, include apertures of different dimensions such that the shunt members of any one core are characterized by a different path length than those included in any other transformer core. The path length of the material surrounding the apertures included in the transformer cores 10, 12 and 14 increases in that order.

The aperture 30 included in each of the cores 10 through 14 is associated with a first amplifier channel and the aperture 31 is included in a second channel. Also, the apertures included in the cores 10, 11 and 12 are ernployed in the first stage of the corresponding amplifier channel, while the apertures 30 and 31 included in the cores 12, 13 and 14 are associated with the second amplifying stage included in the first and second amplifying channels, respectively. The core 12 apertures, included in each amplifying stage of each channel, comprise the output apertures for the first stage, and the input apertures of the second stage.

A plurality of short-circuited iuterstage coupling windings 501, 502, 511, 512 are provided. It is noted at this point that each of the subscripts 1 and 2 employed above was used to designate a particular one of the two amplifying channels included in the FIG. l arrangement. It is also noted that a plurality of additional `circuit elements identified above are further designated by one of the subscripts l through 14 indicating the particular core of the plurality through 14 with which it is associated. Hence, for example, the leg 21'12 corresponds to the shunt leg 21 which is included in the multiaperture core 12 and the winding 511 corresponds to the interstage winding 51 included in the first amplifying channel.

Examining the first stage of the first amplifying channel, it is seen that the short-circuited interstage winding 501 is coupled to the apertures 3010, 3011 and 3012, the winding 501 being coupled to the ferromagnetic material on each side of these apertures in an opposite polarity. It is emphasized that whenever any of the windings 50 or 51 is coupled to any of the apertures 30 or 31, it is in every case linked to the magnetic material on each side of the corresponding aperture in an opposite polarity. Also, while the winding 501 is physically depicted in FIG. l as coupling the apertures 3010 and 3011 through only one turn, it is to be understood that the actual number of turns through which any winding is coupled to a core, if more than one, is designated alongside the coupling winding. Hence, examining the winding 501 it may be seen by the designation 2T that this winding actually links the apertures 3011, and 3011 through two turns while being coupled to the aperture 3012 by one turn.

The coupling winding 511 is coupled to the apertures 3012, 3013 and 301.1 included in the second stage of the first amplifier channel in a manner identically paralleling that described for the first stage of the first channel, with the second channel windings 502 and 512 being similarly connected. Also, two output windings 80 and 81 are respectively connected to the output apertures 3014 and 3114, which are respectively included in the second stage of the first and second amplifying channels. The output windings are linked to the magnetic material on each side of their corresponding apertures in opposite polarities. In turn, the output windings 80 and 81 are connected to an output utilization means 60.

An input information source 30 is provided to supply -information current pulses to two input windings 48 and 49 which are respectively coupled to the input apertures 3010 and 31111 included in the first and second amplifying channels. The source 30 supplies the input binary information to be amplified, with the binary information being manifested by input currents flowing in a selected one of the two possible directions. Hereinafter, currents supplied in the direction of the arrows 110 and 115 shown in FIG. 1 (alongside the input windings 48 and 49) will each be regarded as an input binary 1, and an input 0 is represented by current flowing in the opposite direction.

An enabling current Source 46 is included in the FIG. 1

arrangement to supply a unidirectional current with a ramp-like wave shape of the type illustrated in FIG. 4. An enabling winding 42 is serially connected to the enabling current source 46 and coupled to the cores 10 through 14 with a monotonically decreasing number of turns which are indicated alongside the winding 42 at the junction with the corresponding core. The winding 42 is coupled to the driving legs 20 and 20 included in the transformer cores 10, 12 and 14 to provide a clockwise magnetomotive force throughout these cores when a suitable eurrent pulse is supplied thereto. In addition, the winding 4.2 is coupled to the driving legs 20 and 20', and also the shunt legs 21 and 21', included in the buffer cores 11 and 13 to provide a magnetizing force to these cores also in the clockwise direction. As will be described in detail hereinafter and as depicted in FIG. 4, the enabling winding 42, when energized with a ramp of current from the source 46, sequentially changes the flux state in each of the cores 10 through 14 in that order. The tiux condition of the cross legs 22 included in the transformer cores 10, 12 and 14 is driven from a maximum remanent to a neutral state, while the cross legs 22 included in the buffer cores 11 and 13 are driven between saturated (i.e., maximum remanent) states.

Finally, a readout and reset winding 62, connected to a -readout and reset current source 61, is coupled to a cross leg 22 included in each of the cores 10 through 14- to supply thereto a counter-clockwise, saturating, reset -magnetizing force.

Before describing a typical sequence of circuit operation of the amplifying arrangement shown in FIG. l, the circuit functioning of the core 12, which is typical of the transformer cores 10, 12 and 14, will be discussed along with the convention employed in FIGS. 2 and 3 to illustrate the `magnetic condition for the ferromagnetic core legs of the illustrative core 12. Each vector shown in FIGS. 2 and 3 represents a measure of -magnetic iiux, with a larger vector representing proportionally more flux than a shorter vector. The total additive length of the vectors contained in any particular magnetic member indicates the flux carrying capacity of the member and hence remains constant. Illustratively, the legs 2012, 2012, 2112 and 2112 will in every case each have flux vectors whose total length is two iiux units while each of the cross legs 2212 has flux vectors whose total length is `four units. Accordingly, a total of two flux units is contained in the ferromagnetic material on each side of the apertures 3012 and 3112. It is noted that because of the varying thickness of the transformer cores, the ferromagnetic legs 22 included in the cores 10 and 14 respectively have proportionally less and proportionally ymore flux capacity than the two corresponding legs 22 included in the core 12. When all the vectors in any lmagnetic member have a like orientation thc fluxes are additive and the material is in a maximum remanent condition. When two ivectors are of opposite polarities, the longer of the vectors depicts the direction of the flux flowing through the corresponding member, and the flux has a magnitude proportional to the vector difference. When the flux vectors have a net zero difference, the associated material is magnetically neutral thereby having no net magnetic fiux flowing therethrough.

Assume that the readout current source 61 has last supplied a current pulse to the readout and reset winding 62 to saturate the core 12 in a counter-clockwise, reset polarity as shown in FIG. 2. (This condition will be referred to at times hereinbelow as positive saturation.) Note in FIG. 2 that the units of flux flowing through all cross sections of any individual one of the members 2012, 29,12, 2112, 21,12, and 2212 are identical, and tiux is conserved in each junction between any of the members. Hence, the fundamental physical principle that lines of flux be continuous is satisfied.

Assume now that a current in the direction of the arrow 210 in FIG. 2 is flowing in the winding. 501 towards the aperture 3012, and that a current is ilowing in the opposite direction, as indicated by the vector 213, in the winding 502 coupled to the aperture 3-112. When the enabling source 46 next supplies the winding 42 with a current ramp which has attained the minimum switching threshold for the core 12, shown as time c in FIG. 4, the winding 42 generates a ma-gnetomotive force which reverses the remanent hysteresis magnetization orientation of the driving leg 21112 from its previous right-toleft direction illustrated in FIG. 2 to a left-to-right orientation as illustrated in FIG. 3. Similarly, the driving leg 2012 switches its flux orientation and resides in a right-to-left orientation as shown in FG. 3. Note that two units of ux now flow from left to right in FIG. 3 in the leg 2012 and return right to left in the shunt leg 2112. Also note that two units of ux flow in a closed magnetic path including the driving leg 20'12 and the shunt leg 2112. It is apparent that the energized driving winding 42 must also supply a switching magnetizing force to reverse two ux units in the cross legs 22 as no net flux can exist in either 4of these members under the abofve-described magnetic state of the driving legs 2012 and 2012 and shunt legs 2112 and 2112. If any iiux were contained in either of the legs 2212 it would have to be returned through either a driving leg or a shunt leg, as lines of flux must be continuous, as mentioned above. However, each of the driving legs 2612 and 2012 and shunt legs 2112 and 2112 is in a maxi-mum remanent condition and, moreover, the driving leg 2012 and shunt leg 2112, and the driving leg 24112 and shunt leg 2112, already have two continuous units of flux flowing therethrough in two closed, cornpleted, magnetic paths. Hence, each of the cross legs 2212 is driven by the aforementioned switching signal supplied by the source 56 from a saturated condition to a neutral condition, as illustrated in FIG. 3.

The currents supplied to the windings 5011 and 5tl2 shown in FIG. 2 produce counter-clockwise and clockwise magnetizing forces, respectively around the `apertures 3G12 and 3112. These magnetizing forces aid in switching winding magnetomotive force in the core material to the right of the apertures 3012 and 3112 while opposing the switching magnetizing force -on the opposite sides of these apertures. It is a well known physical principle of magnetics that the speed of domain wall motion, and thereby also the speed of square loop magnetic switching, is directly proportional to the applied magnetizing force. Therefore, since a larger force is applied to the material to the right of the apertures 31112 and 3112 than to the opposite sides of these apertures, the harder-driven material switches at a more rapid rate of speed. Since the total flux switched in the cross legs 2212 is constrained to be two flux units, a greater portion of these two flux un-its is switched in the faster-switching righthand material contiguous to the apertures 3912 and 3112, resulting in the magnetic condition illustrated in FIG. 3.

As mentioned above, the windings 511 and 512 are also coupled to the material on either side of the core apertures 3012 and 3112, respectively in an opposite polarity. Hence, the signals induced by the switching of ux in the material on either side of a cross leg aperture ordinarily tend to have a cancelling effect on one another. However, as a larger flux change has occurred in the material to the right of the apertures 3012 and 3112 than transpired on the other side thereof, the fasterswitching right-hand material induces a proportionally larger signal in each of the coupling windings 511 and 512 than does the slower-switching left-hand material, which undergoes a smaller iiux change. Hence, by a simple application of Lenzs Law, it is apparent that voltages are induced in the windings 511 and 512 in the polarities shown in FIG. 3.

The core 12 is reset to its initial, reset magnetization condition illustrated in FIG. 2 by the next energization 6 signal supplied to the readout winding 62 upon completion of the amplification process. At that time the next current pulse supplied to the Winding 62 coupled to the cross legs 2212 produces a counter-clockwise maximum remanent flux throughout the core 12 by switching two units of llux in each of the core legs 2212, 2012 and 20'12.

It is noted that the above-described operation is illustrative of the circuit functioning for each of the transformer cores 10, 12 or 14. The switching process in each of the bufer cores 11 or 13 is identical to that described above for the transformer cores, except that the energized switching winding 42 drives the buffer cores from a saturated state through neutral, and to the opposide remanent condition, by switching two units of flux in both the driving and shunt legs included therein. Information is put into the buffer cores during the transition from saturation to neutral, and is read out of these cores as the flux condition thereof progresses from neutral to the other remanent condition.

With this basic core function in mind, a typical cycle of amplification for the FIG. 1 arrangement will now be described. Assume first that the reset current source 61 supplies a current to the readout and reset winding 62 which saturates each of the cores 1t? through 14 in the initial, counter-clockwise, maximum remanent condition, shown for the core 12 in FIG. 2.

Assume now that the input information source 30 supplies a binary l input signal to the input winding 48 (i.e., current flowing towards the aperture 3010), while also supplying a binary 0 signal to the winding 49 (i.e., current flowing away from the aperture 3110). Coincident with the input signals being supplied to the core 11i, the enabling source 46 begins to supply a ramp of current to the driving winding d2. As the winding 42 is coupled to the cores 1@ and 11 with the greatest number of turns, these cores have the lowest switching current threshold, and the energized winding 42 eventually switches flux in the cross legs thereof at the times a and b, respectively, shown in FIG. 4. It is noted that the winding 42 is coupled to the cores 10 and 11 with 20 and 19 turns, respectively, to allow the core 10 to begin switching slightly prior to the core 11. This compensates for the unavoidable, inherent delay in translating signals from the core 10 to the core 11 due to finite core switching time and the reactance associated with the coupling winding 501. The crossl legs 2210 included in the core 1li are thus driven from their previous saturated cond1- tion to a neutral magnetic condition, and the currents supplied by the input windings 48 and 49, respectlvely, produce clockwise and counter-clockwise magnetic flux perturbations around the apertures 30111 and 3110 1n the manner described in detail above with respect to the core 12, and as illustrated in FIGS. 2 and 3. Whlle these liux perturbations around the apertures 31110 and 3110 are being established, a current is induced 1n each of the coupling windings 501 and S02 coupled to the apertures 3G11, and 3110 in the directions indicated by the arrows 12) and 125 shown in FIG. l alongside the wlndings 501 and 502, respectively.

The current in the winding 501 produces a clockwise flux around the aperture 3011 associated with the core 11 which is at the time b also -being driven, in response to the current supplied to the winding 42, from a condition of positive saturation to a condition in which its cross legs are magnetically neutral. It is noted that the current in the winding 501 does not have any effect on the magnetic state of the ferromagnetic material surrounding the aperture 3612 to which it is also coupled because of its relatively small magnitude. In Iorder for an energized short-circuited coupling winding to have any effect on the magnetic condition of the material surrounding a core aperture, a change in the flux throughout the entire core from a saturated state to a neutral state is coincidentally required. This difference in susceptibility to '5? have imparted thereto a flux perturbation around a cross leg aperture during the time when the cross legs are saturated, and when they are being driven between maximum remanence and neutral, is one of the fundamental properties of the multi-apertured cores through 14.

At the times c and d illustrated in FIG. 4, when the cross legs of the buffer core 11 have reached a neutral magnetic condition, the number of turns of the switchingy winding 112 coupled to the transformer core 12 and the buffer core 13, along with the rate of rise of the current ramp supplied by the source 46, are sufficient to initiate the switching process in the cores 12 and 13 for the reasons set forth with respect to the cores 10 and 11, the winding 42 is coupled to the cores 12 and 13 such that switching in the core 12 slightly precedes any flux reversal in the core 13. Note, as hereinbefore mentioned, that the coupling winding 501 is coupled to the apertures 3010 and 3011 with two turns, while being coupled to the aperture 3012 by only one turn. Hence, as the fiux unbalance was being propagated from the core 10 to the core 11, it essentially underwent no change in magnitude. However, at the time when the cross legs 2211 included in the core 11 are being driven from neutral to negative saturation, thereby inducing a current in the winding 501 in the direction of the vector 120, the legs 2212 of the core 12 are being driven from positive saturation to neutral. As no net voltage can exist in a short-circuited winding, the flux coupled to such a winding must have a net value of zero. Therefore, as the winding S01 is coupled by twice the number of turns to the aperture 3011 than it is to the aperture 3012, the current induced in the winding 501 must produce twice the net fiux unbalance in the ferromagnetic material surrounding the aperture 3012 than had previously existed around either of the apertures 3010 or 3011. Hence, there has been a flux gain of approximately two between the input information read into the ferromagnetic material surrounding the input aperture 3010 and that which finally resides in the material surrounding the aperture 3012 included in the second transformer core 12.

Also note that the path length of the ferromagnetic material on either side of the aperture 3012 is longer than the path length around either of the apertures 3010 or 3011. As the coercive force required for switching is a direct function of the path length, the current which exists in the short-circuited coupling winding 501 at the time the core 12 is switched from saturation to neutral is greater than the initial input current supplied by the input Winding 48. It is noted that this higher current has no effect in the backwards direction around the previous transformer core aperture 3010, as the cross legs 2210 of this core are being held in a neutral state by the energized winding 42.

It should be observed at this point that there has been an increase in the signal energy stored in the ferromagnetic material surrounding the aperture 3012 as compared t-o that included around the input aperture 3010. As is well known, the energy stored by a remanent condition in a ferromagnetic material is a bulk property of the material, and therefore directly proportional to the product of the magnitude of flux in a material times the path length through which the flux flows. Note here that the energy gain is manifested by approximately twice the number of lines of signal flux fiowing around the aperture 3012 as compared to the aperture 3010, which flux, moreover, flows through a longer path length.

Proceeding to the second amplifier stage included in the first amplifier channel, information is transferred by the short-circuited coupling winding 511 from the aperture 3012 to the aperture 3013. As the winding 511 is coupled to these two apertures with a like number of turns, approximately the same signal flux is read intovthe buffer core 13 as exists around the aperture 3012. Finally, at time e shown in FIG. 4, the source 46 supplies a current of a sufiicient magnitude to switch the final transformer core 14 from a maximum remanent to a neutral condition at the time when the buffer core 13 is being driven from a neutral to a negative saturation magnetic condition, and the signal flux stored in the buffer core 13 again energizes the coupling winding 511.

As noted hereinabove with respect to the first stage of the first amplifier channel, the buffer core 13 is coupled to the Winding 511 with twice the turns as is the final transformer core 14, and hence twice the amount of Signal flux is induced around the final second stage aperture 3011 as was included around the intermediate aperture 3013. Hence, the signal flux which finally resides in a counter-clockwise direction around the aperture 301.1 is four times greater than the quantity initially supplied to the input aperture 3010. Also, the path length around the aperture 301.1 has been made longer than that included around any of the apertures included in previous transformer cores. It is noted that the increased current iiowing through the winding 511 does not propagate any intelligence in the backwards direction as the core 12 is at this time held in a neutral magnetic state, thereby rendering the switching threshold around the aperture 3012 to which the winding 511 is coupled to be of a relatively high value. The reluctance to switching in the backwards direction around the aperture 3012 is further enhanced by the presence of the unsaturated material surrounding the aperture 3010 which is coupled to the aperture 3012 by the short-circuited coupling winding 501.

In a manner identically paralleling that described above, the binary "0 signal supplied by the input winding 49 to the aperture 3110 is finally manifested by a around the aperture 311.1, with a magnitude four times greater than the initial signal read into the core 10. Also, this magnified flux flows through a longer path length.

The amplified information may be read out when denet flux perturbation in the clockwise direction flowing sired by a current pulse supplied by the readout current source 61 in the direction of arrow 65 to the readout winding 62. The energized winding 62 saturates each of the cores 10 through 14 in a counter-clockwise maximum remanent condition thereby supplying output signals from the apertures 3011 and 3114, to the output windings and 81, and thereby also to the output utilization means 60. Both channels of the amplifier are then in their initial magnetization states ready to initiate a new cycle of operation.

It should be noted at this point that in amplifying the input signals, both an increase in flux, and also an increase in the path length through which the flux flows, have been employed. It should be apparent that an energy gain would result if either one, as well as both of these quantities are increased. Therefore, the FIG. 1 arrangement may be modified to amplify the signal energy by solely employing longer path lengths without an associated flux gain by simply making all cores of a like thickness, and coupling the windings 501, 502, 511 and 512, to the associated cores 10 through 14 with a like number of turns. Similarly, an energy gain manifested by a flux increase without the presence of an increase in the path length is created by constraining the path length of the ferromagnetic material surrounding each aperture included in each of the transformer cores 10, 12 and 14 to be of the same length. In both of the above-described alternate embodiments, it is apparent that there exists an energy gain manifested by signal fiux flowing through a greater quantity of ferromagnetic material around the output apertures included in the core 1li than existed around the corresponding core 10 input apertures.

It is apparent that for noise considerations flux flowing in the cross legs 22 of the cores 10 through 14 should advantageously have a propensity for dividing equally in the ferromagnetic material on each side of each of the apertures 30 and 31 in the absence of any energized conductors passing through the aperture. To enhance this flux division, the outer extremities of the rectangular core apertures formed by the driving legs and 20 with the shunt legs 21 and 21', respectively, are made colinear with the centers of the apertures 30 and 31. This symmetry aids the balancing of iiux in the cross legs 22.

Also, only one of the driving legs 20 and 20 and an associated one of the shunt legs 21 and 21 is, in fact, essential for circuit operation, and the redundant members may simply be replaced by a magnetic member having no windings linked thereto and characterized by a like iiux capacity as each of the cross legs 22. However, the two driving legs 20 and 20 and the two shunt legs 21 and 2,1 are employed in the illustrative embodiment shown in FIG. l simply to make the core symmetrical and thereby further enhance the balancing of flux in the cross legs 22 associated therewith.

Summarizing, an illustrative magnetic core amplifying arrangement made in accordance with the principles of the present invention employs -a plurality of multiapertured magnetic cores. Each core includes a driving leg in parallel with a shunt leg of the same cross-sectional area, and at least one cross leg is provided to complete a closed magnetic path which also includes the driving leg. The cross leg has a uniform cross-sectional area which is twice the magnitude of that possessed by each of the associated driving and shunt legs, and an aperture is centrally located in the cross leg. The cores are subdivided into buffer cores including cross leg apertures of a like dimension and transformer cores including cross leg apertures of different dimensions. In addition, the transformer cores are each characterized by a different thickness. A plurality of short-circuited windings are each coupled to the apertures included in one buffer core and two transformer cores, the windings being coupled to the ferromagnetic material on either side of each associated aperture in an opposite polarity.

A driving winding is provided to switch the flux condition of the cores in `a sequential manner. As the transformer cores are driven in turn between a maximum remanent and a neutral magnetic condition, input information supplied to the transformer core including the smallest aperture is propagated to finally reside in an amplified condition in the largest-apertured transformer core.

It is to be understood that the above-described arrangements are only illustrative of the application of the principles of the present invention. Numerous other arrangements may be devised by those skilled in the art Without departing from the spirit and scope of this invention. For example, a two-channel, two-stage amplifier was illustrated for purposes of clarity and simplicity. It is manifest, however, that, corresponding to an n-channel, k-stage amplifier, 2k+l multiapertured cores are employed, with n apertures included in the cross legs of each core.

In addition to functioning as an amplifying structure, it is noted that the FIG. 1 arrangement may be modified to generate sequential binary combinatorial logic. Specifically, by replacing a plurality of the transformer cores 10, 12 or 14 in FIG. l with multileg logic computing cores of the type shown in my copending application, Serial No. 241,261, filed November 30, 1962, the resulting arrangement can perform several sequential logic functions for a single current ramp supplied by the source 46 to the winding 42. Such four-legged logic elements as shown in FIGS. 2 and 3 of the aforementioned application, for example, can generate logic functions of two independent variables, so that the output signals from the device when the logic elements are substituted for the transformer cores represent a particular logic function of the input signals. However, the amplifying capability is retained after the substitution even though the function of the device is then primarily to generate sequential binary combinatorial logic. The substituted logic elements cooperate with the amplifying cfharacter of the device to produce the desired amplified logic output. Therefore the need for a transistor or other type of amplifier to increase the energy of the output logic signals is largely obviated.

What is claimed is:

1. In combination in a magnetic amplifier, two multiapertured transformer cores and a multiapertured buffer core, each of said cores including a cross leg and a driving leg which completes a closed magnetic path through said cross leg, a leg connected in shunt with each of said driving legs, each of said cross legs being apertured to form two equal-length shunt magnetic members, said transformer cores respectively including shunt cross leg members of different effective magnetic lengths, and a shortcircuited winding coupled to the shunt magnetic members included in said transformer cores and said buffer core, said winding being coupled to each of said shunt magnetic members of each of said cores in an opposite polarity.

2. A combination as in claim 1, further including a driving winding coupled to the driving leg of each of said transformer cores `and coupled to said driving and shunt legs of said buffer core, said winding being alternately connected to each of said transformer and said buffer cores with a monotonically decreasing number of turns.

3. A combination as in claim 2 wherein said cross legs included in different ones of said cores are characterized by different flux capacities.

4. A combination as in claim 3 further including an information source and an input winding connected to said information source and coupled to said aperture included in said transformer core characterized by the shunt magnetic members of lesser effective magnetic length.

5. A combination as in claim 4 further including an output winding coupled to said aperture included in said transformer core characterized by the shunt magnetic members of greater effective magnetic length, an output utilization means serially connected to said output winding, and a current source for supplying a monotonically increasing ramp of current to said driving winding.

6. In combination, first, second and third magnetic circuits each comprising two shunt, equal-length magnetic members, the magnetic members in said first `and third magnetic circuits being characterized by different magnetic path lengths, and a short-circuited w-inding coupled to each member of each of said magnetic circuits, said winding being coupled to one of said members of each of said magnetic circuits in a first polarity and coupled to the other of said members in :a second and opposite polarity.

7. A combination as in claim 6, wherein said shunt magnetic members included in said first and third magnetic circuits are further characterized by different fiux capacities.

8. A combination as in claim 7 wherein said shortcircuited Winding is coupled to each of said shunt magnetic members included in said first and second magnetic circuits with a like number of turns which exceeds the number of turns with which said winding is coupled to each of said shunt magnetic members included in said third magnetic circuit.

9. A combination as in claim 8 further comprising means for saturating each member included in each of said magnetic circuits, first switching means for supplying a switching magnetizing force to each member included in said first and second magnetic circuits, and second switching means for supplying a switching magnetizing force to each member included in said second and third magnetic circuits `at a time following the initiation of each switching force supplied by said first switching means.

10. A combination as in claim 9 further comprising an input source, an input winding serially connected to said input source and coupled to said shunt magnetic members included in said first magnetic circuit, an output utilization means, and an output winding serially connected to said output means and coupled to said shunt magnetic members included in said third magnetic circuit.

11. In combination in a k-channel n-stage magnetic amplifier, where k and n are independent, positive integers,

lz-i-l transformer cores and n buffer cores, each of said cores including a cross leg, k apertures centrally located on the cross leg of each of said cores, iirst flux source means included in said transformer cores for supplying to said core cross legs a magnetic flux which alternates between a remanent saturation and a neutral magnetic condition, said buffer cores including second tlux source means for supplying to said associated buffer core cross legs a magnetic flux which varies between remanent saturation conditions, said cross legs included in said transformer cores being characterized by different Hux capacities, and short-circuited winding means coupling corresponding apertures included in said cores.

12. A combination as in claim 11 wherein the ferromagnetic material on either side of each of said cross leg apertures included in different ones of said transformer cores is characterized by a different magnetic path length.

13. A combination as in claim 12 further comprising k input signal sources and k input windings, each of said k windings being connected to a diiferent one of said k input sources and coupled to a different one of said k apertures included in said transformer core cross leg characterized by the smallest value of ilux capacity.

14. A combination as in claim 13 further comprising an output utilization means and k output windings connected to said output utilization means, each of said k windings being coupled to a different one of said apertures included in said transformer core cross leg characterized by the greatest value of flux capacity.

15. In combination, a plurality of magnetic circuits, each circuit inclding a flux source and two equal-length shunt-connected magnetic members connected to said ux source, said magnetic members included in different ones of said magnetic circuits being characterized by different path lengths, an input winding coupled to each magnetic member of one of said magnetic circuits and a shortcircuited coupling winding coupled to each magnetic member included in each of said magnetic circuits.

16. A combination as in claim 15 wherein said magnetic members included in each of said magnetic circuits are characterized by a different value of flux capacity.

17. A combination as in claim 2 further including an information source, an input winding connected to said information source and coupled to said aperture included in said transformer core characterized by the shunt magnetic members of lesser effective magnetic length, an output winding coupled to said aperture included in said transl2 former core characterized by the shunt magnetic members of greater effective magnetic length, an output utilization means serially connected to said output winding, and a current source for supplying a monotonically increasing ramp of current to said driving winding.

18. In combination, 21z-|-l magnetic circuits each comprising k pairs of shunt equal-length magnetic members, Where n and k are independent positive integers, each of said pairs included in each of said magnetic circuits being associated with a different channel, the magnetic members in alternate ones of said magnetic circuits being characterized by different ux capacities, and short-circuited winding means coupled to said pairs of shunt magnetic members associated with each channel, said winding means being coupled to each of said shunt magnetic members of each of said pairs in an opposite polarity.

19. A combination as in claim 18 wherein said shortcircuited winding means is coupled to a plurality of said pairs of shunt magnetic members associated with each channel with a like number of turns which exceeds the number of turns with which said winding means is coupled to the others of said pairs associated with each channel.

20. A combination as in claim 19 further comprising means for saturating each member included in each of said magnetic members, switching means for supplying switching magnetizing forces to each member included in said magnetic circuits, k input signal sources and k input windings, each of said k input windings being connected to a different one of said k input sources and coupled to a different one of said k pairs of shunt magnetic members characterized by the smallest value of flux capacity, and an output utilization means and k output windings connected to said output utilization means, each of said k output windings being coupled to a ditferent one of said lc pairs of shunt magnetic members characterized by the greatest value of uX capacity.

References Cited by the Examiner UNITED STATES PATENTS 6/1961 Mallery 307-88 9/1963 Haynes. 

1. IN COMBINATION IN A MAGNETIC AMPLIFIER, TWO MULTIAPERTURED TRANSFORMER CORES AND A MULTIAPERTURED BUFFER CORE, EACH OF SAID CORES INCLUDING A CROSS LEG AND A DRIVING LEG WHICH COMPLETES A CLOSED MAGNETIC PATH THROUGH SAID CROSS LEG, A LEG CONNECTED IN SHUNT WITH EACH OF SAID DRIVING LEGS, EACH OF SAID CROSS LEGS BEING APERTURED TO FORM TWO EQUAL-LENGTH SHUNT MAGNETIC MEMBERS, SAID TRANSFORMER CORES RESPECTIVELY INCLUDING SHUNT CROSS LEG MEMBERS OF DIFFERENT EFFECTIVE MAGNETIC LENGTHS, AND A SHORT- 